Abstract:

A solar radiation collector system may includes a gimbal with a rim that
supports a solar radiation concentrator or collector assembly passing
through the plane of the rim, and foundation structures that support and
anchor the gimbal, allowing it to both rotate and be raised or lowered.
One flexible structural member may support the gimbal rim and a second
flexible structural device both anchors the rim and enables the
gimbal-collector assembly to rotate around an axis parallel to the
earth's polar axis providing the desired primary tracking motion
following the daily apparent motion of the sun. Motion between the gimbal
and the solar radiation collector assembly allows the assembly to follow
the apparent seasonal motion of the sun, among other tasks.

Claims:

1. A solar radiation collector system, comprising:a ground support; anda
gimbal rotatably anchored at a first part of the ground support device to
have a rotation orientation, the gimbal comprising:a gimbal rim mounted
on the gimbal, which supports at least one radiation transducer element;a
suspension member, connected to a second part of the ground support
device, suspending the gimbal rim; anda capture device which connects to
a driver and passes over the gimbal rim to rotate the gimbal rim and keep
the gimbal rim in contact with the suspension member,wherein the rotation
orientation desired for tracking motion is adjusted for an apparent
motion of the sun.

2. The solar radiation collector system according to claim 1, wherein the
second part of the support device is at least one polar column.

3. The solar radiation collector system according to claim 1, further
comprising a declination driver mounted for the gimbal and a concentrator
assembly to provide a declination motion between the concentrator
assembly.

4. The solar radiation collector system according to claim 1, wherein the
ground supports in conjunction with the rotatable capture devices and
suspension members can enable common tools operated by hand to raise and
lower the gimbal.

5. The solar radiation collector system according to claim 1, wherein the
gimbal is anchored on the first part of the ground support through at
least one bearing.

6. The solar radiation collector system according to claim 1, wherein a
face of the radiation transducer element is generally perpendicular to a
face of the gimbal rim.

7. The solar radiation collector system according to claim 6, wherein the
face of the radiation transducer element passes through the gimbal rim.

8. The solar radiation collector system according to claim 1, further
comprising a receiver mounted at the focus of the radiation transducer
element.

9. The solar radiation collector system according to claim 1, wherein the
suspension member comprises a flexible force transmitting member.

10. The solar radiation collector system according to claim 1, wherein the
gimbal rim is polygonal.

11. The solar radiation collector system according to claim 10, wherein
the gimbal rim further comprises at least one roller at an apex of two
sides of the polygonal rim, the roller being configured for rolling on
the suspension member.

12. The solar radiation collector system according to claim 11, wherein
the capture device passes over at least one of the rollers.

13. The solar radiation collector system according to claim 1, wherein the
gimbal further comprises a capture device opposite the suspension member,
and the driver is connected to the capture device.

14. The solar radiation collector system according to claim 13, wherein
the gimbal further comprises a redirection mechanism on the opposite side
of the driver and the capture device connected to the driver and the
redirection device.

15. The solar radiation collector system according to claim 1 wherein the
suspension member comprises a pair of suspension collars and a suspension
member.

16. The solar radiation collector system according to claim 1, wherein the
driver is integrated with the gimbal rim and moves with the gimbal rim.

17. The solar radiation collector system according to claim 1, wherein the
capture device entirely surrounds the gimbal rim and is utilized by the
driver.

18. The solar radiation collector system according to claim 1, wherein an
axis of rotation is parallel to the axis of the earth.

19. A solar radiation collector system, comprising:means for ground
support coupled with a gimbal configured for rotatably supporting the
gimbal at a given orientation from the ground, the means for ground
support including a first means for rotatably suspending and capturing
the gimbal, and providing three dimensional stability and including
second means for raising, lowering and changing orientation of the
gimbal;structural means for carrying at least one radiation transducer
device connected with the gimbal;means for receiving solar radiation
directed to it by at least one radiation transducer element;first means
for imparting rotational movement for the gimbal to effect a desired
primary tracking motion to adjust for the apparent daily motion of the
sun; andsecond means for moving the structural devices carrying at least
one radiation transducer device to provide for a second dimension
adjustment for the apparent seasonal motion of the sun.

20. A method for assembling a solar radiation collector comprising:fixing
a ground support on the ground;assembling a gimbal with a gimbal rim at
one end of the gimbal;lifting the gimbal onto a second part of the ground
support;redirecting the gimbal, so at least one part of the gimbal rim is
close to the ground;assembling a transducer element on the gimbal
rim;anchoring a bottom of the gimbal on a second part of the ground
support; andadjusting a face of the transducer element so the transducer
element can face the sun.

[0004]A typical related art concentrating solar collector system includes
a concentrator having a suitable reflective surface which may be
monolithic or formed from multiple individual mirrors, a receiver for
absorbing the concentrated solar radiation, and associated support
structures. Point-focus solar collector systems also require suitable
primary and secondary tracking devices so that aligned mirrors can follow
the apparent movement of the sun from dawn to dusk and through seasons.
Such collector systems are arranged and constructed so that the sun's
rays falling on reflective surfaces are directed into receivers to be
utilized in any well known manner, such as heating a suitable circulating
fluid which can be used to power an engine or be transported elsewhere
for various uses, applying it directly to photovoltaic or other suitable
direct energy conversion devices, utilizing it in a solar reactor for a
variety of chemical processes, and the like. A receiver can be arranged
to move with the concentrator or be fixed with respect to the moving
concentrator assembly.

[0005]The related art is replete with a multitude of different designs of
solar collector systems and tracking structures. Such related art systems
have not been practicable and were typically complex, heavy and onerous
to erect and service. Not a single one has met the commercial
requirements of the marketplace. Current designs require subsidies for
them to make economic sense, and these solar collectors typically take
many years to replace the energy invested in materials and installation.

[0006]The related art has a variety of solar collectors that feature
methods of lifting and lowering structures. For example, one type of
technology can utilize a polar column hinged at the base and a pivoting
equatorial mount to lift and lower a solar collector mounted between
them. To support the concentrator and receiver, central structural
devices with a shaft at each end have been suggested. An independent
drive wheel or gear may rotate the concentrator to follow the sun.
However, this type of technology does not accommodate solar seasonal
motion. Another technology rotates the concentrator assembly around the
receiver to track seasonal motion. Both these approaches would require
very substantial central structures ending in significant shafts to
accommodate the forces concentrated there into bearing devices at each
end. Lacking adequate force distribution, wind and gravity loads would
tend to twist and deform both kinds of structures.

[0007]The related art may utilize rings that are perpendicular to a right
ascension, RA, axis that enable tracking in this dimension. Methods are
also mentioned for tracking in declination. However, these related arts
cannot transmit wind and gravity loads on the tracking structures into
the foundations without great distortion nor do they illustrate
alternative force distribution structures. None of the related art
mentions associated foundation structures to raise and lower these solar
collectors.

[0008]The related art illustrates ways to distribute gravity and wind
forces involved in turntable-type structures that provide the primary
tracking motion and that use integral accurate ring or rings to provide
the secondary tracking motion. The related art may mention how to
distribute loads in the secondary tracking structure. However, these
forces have to be accommodated by the turntable arrangement that requires
extensive foundations with a heavy accurate ring. One solution for field
construction mentioned is to assemble the solar collector or heliostat in
a building with required access to elevated assemblies and then to
transport the completed unit to the site using heavy equipment. One of
the related arts does not distribute forces in the secondary tracking
structure but requires slender members that would rapidly fatigue, riding
on four small rollers, and this approach would also require heavy
equipment for erection. The very large offset overturning moments
involved when high winds impact the elevated sail area of these
concentrators would tend to pry both these approaches off turntable
interfaces at ground level.

[0009]Multiple columns to raise and lower a concentrator have been
suggested but this patent teaching would be primarily effective only near
noon in tropical regions where the sun is nearly directly overhead. At
other times and places, since the receiver is stationary, it would be
difficult to get the concentrator shape appropriate for off-axis
conditions. The reflective surface always faces skyward and, with
multiple independent cable winches, would be extremely difficult to
control. The associated receiver would require heavy equipment for
installation. There seems to be no mechanism for stabilizing this kind of
concentrator so that regions do not invert, like an inside-out umbrella,
in high winds.

[0010]Another technology encountered major problems while trying to
support a curved rim on two rollers. To prevent metal fatigue from
concentrated forces at the two rollers, the curved structural member
either has to be very robust and preferably heat treated like a railroad
rail or the rollers have to be soft, like a rubber tire. In addition, not
only were these large curved members difficult to form and transport,
mounting an assembled solar collector on the columns required heavy
equipment. Suspending the curved rim on multiple rollers mounted on a
chain, in roller-chain style, between two columns did distribute the load
but, mounted at the angle required for installations in the US, keeping
the rollers tracking properly proved difficult. Although this method
would work near the equator, where the curved rim is almost vertical, it
is difficult to support the rollers working with RA axes at higher
latitudes. It was also difficult, using this method of construction, to
lift the structure off the ground.

[0011]Another technology which supports transducer devices on two polar
columns provides supporting a third point on the tracking structure for
providing stability and provides a way (tilting) to raise and lower the
equipment. However such technology is used for supporting a heliostat and
thus does not teach rotating an assembly to follow the sun, nor does it
provide a way to operate in windy conditions.

[0012]Three issues have impeded deploying viable large solar collectors
that harvest enough solar energy so they can become the preferred
renewable energy resource: [0013]1. Wind loads (managing forces on the
structure, through drives and into the ground); [0014]2. Hail, freezing
rain, snow, frost and soiling (maintaining active area performance); and
[0015]3. High erection and maintenance costs (structure, interface and
foundation approach).Collecting significant amounts of solar energy
requires a large area of reflector to redirect sunlight into a receiver.
This reflector area acts like a sail and since they must follow the sun,
concentrators at any orientation must transmit wind loads, coming from
any direction, into the ground. To stay clean as possible, to prevent
hail from damaging mirrors and to minimize exposure to wind, reflectors
must face down when not operating. When facing skyward, hail may damage
transducer elements (including both mirrors and photovoltaic approaches)
and they accumulate dust, snow, freezing rain and frost. Because mirrors
reflect and do not absorb radiation, sunlight warms them very slowly and
ice deposits take a long time to melt, delaying operation and wasting
energy. Utility-scale point-focus solar collectors (that have more than
800 square feet of reflector) and many smaller units all require heavy
equipment both for erection and for repairing drives and bearings.
Scheduling heavy equipment can be problematic. Cost to bring in a crane
can exceed the value of energy a collector harvests in a year. Also,
fossil carbon footprint accounting requires renewable energy equipment
replace the resources used in manufacturing, construction and maintenance
including fuel burned by heavy equipment. Erecting and repairing solar
collectors should minimize using fossil fuel powered equipment.

[0016]Related art designs of heliostats and point-focus solar collectors
utilize a variety of tall columns as in FIG. 1 through FIG. 3, or a
turntable with elevated collector pivots as in FIG. 4. Each of these
approaches requires a crane to lift and mount the collector assembly
respectively between the columns, to the top of the single pedestal or
between the elevated pivots of a turntable.

[0017]Referring now to the drawings, FIG. 1 and FIG. 2 illustrate two
related art two-axis tracking, point focusing, solar collector systems 30
shown as equatorially oriented structures wherein systems have two
motions: one, around the right ascension, RA, axis 49 parallel to the
earth's polar axis and the other, around axes generally perpendicular to
the RA axis. The solar radiation collector systems 30 include a main
support structure 32 with a concentrator frame 36 for carrying one or
more transducer elements. Reflective transducer elements 37 are supported
and positioned either on transducer support members 43 connected with
frame 36 in FIG. 1 or on linear transducer assemblies 41, seven in each
of four quadrants, are illustrated in FIG. 2 to create a Fresnel
reflective paraboloidal surface. These systems require suitable receivers
48 connected either to the main support structure 32 as shown in FIG. 1,
or on dedicated support devices in front of the concentrator assembly 35
illustrated as two booms 40 in FIG. 2, so they move with the tracking
structure. Receivers 48 are arranged for receiving the solar radiation
directed from the transducer elements 37.

[0018]A desired primary tracking motion (right ascension) 49 rotates the
main support structure with respect to the ground to counteract the
rotating earth. The solar collector shown in FIG. 1 utilizes a friction
drive roller 70 mounted on a motor-driven gear reducer of the right
ascension drive 69 that directly turns the main support structure 32
around the RA axis 49. Shown in FIG. 2, the motor/gear reducer of the
collector right ascension drive 69 that is fixed to the RA axis support
72 turns a small diameter sprocket that engages a drive wheel 71 attached
to the main support structure 32.

[0019]To provide for the second motion (declination) 47 to adjust for the
tilt of the earth responsible for seasonal changes in solar position, the
transducer elements 37 are arranged and constructed to provide for the
selective movement thereof with respect to the frames 36. That is, the
reflective surface is of the dynamic Fresnel element type wherein the
Fresnel mirrors, or other suitable transducer elements, are arranged to
be selectively moved on axes generally perpendicular to the RA axis 49 to
accommodate the seasonal variation of the solar position. Because the
receiver 48 is typically on the optical axes of the two systems 30
illustrated in FIG. 1 and FIG. 2 only at equinox, the reflective surface,
the mirror facets, or other transducer elements thereof must be adjusted
to function properly at other times of the year. Conveniently, this can
be achieved by moving facets individually, FIG. 1, by linear motion 68 of
a member connecting rows of transducer elements 37 causing them to rotate
or mounting the transducer elements on suitable transducer assemblies 41,
FIG. 2, which are disposed within the frame 36 and provided with drive
devices for selectively rotating them.

[0020]Although such related art dynamic Fresnel type concentrator solar
collector systems have operated entirely satisfactorily with respect to
the ability to concentrate and collect solar energy, they have remained
too difficult to manufacture and erect to be entirely acceptable for many
promising near term commercial applications. For example, such systems
require either substantial columns to support large concentrators, or
involve many foundations for both support columns and guy cables 53. The
cables that anchor the columns to foundations and those mutually
stabilizing the solar collector are difficult to see, especially in dim
light, and avoiding them requires extraordinary care. Although the solar
collector of FIG. 1 has three primary foundations: the two polar columns
59 and the equatorial foundation 52 with RA axis support 72, it also
requires a foundation to anchor the tie down 64 that prevents wind from
polar directions from overturning the assembly. The solar collector in
FIG. 2 requires two polar foundations 50 and two equatorial foundations
52 to support the bifurcated polar structure 59 and RA axis support 72
along with six additional foundations to secure cable stays 53 to the
ground.

[0021]FIG. 3 shows a typical point-focus solar collector mounted on a
single pedestal 51. An azimuth drive rotates the tracking structure
around a vertical axis 44 and an elevation drive pivots the concentrator
and receiver around a horizontal axis 42. The center of gravity of the
moving structure is ideally located where these axes intersect to
minimize drive torque requirements. The concentrator frame 36 is mounted
on one end of the main support structure 32, with the receiver 48 mounted
on the other end. Assemblies of mirror facets 37 are attached to the
concentrator frame 36. To stow the collector 30, the concentrator
assembly 35 rotates up until it is partially inverted and the receiver 48
moves down to a limit set by interference between the single pedestal 51
and the main support structure 32. Both the azimuth and elevation drives
that interface with the top of the central pedestal 51 are compact which
requires an assembly with extraordinary strength and precision.

[0022]FIG. 4 shows a point focus solar collector mounted on a turntable 60
that has a central hub 38. The large diameter turntable structural member
rides on rollers on top of many columns 61 which prevents snow and ice
from interfering with operation. Wrapping a roller chain around the
outside diameter of this turntable allows a stationary gear motor with a
sprocket to effectively drive this solar collector system 30 around the
vertical axis 44. Uplift is prevented by capturing the central hub 38 on
the central column or providing uplift prevention devices on the column
and roller assemblies 61. Two symmetrical main support structures 32 are
each topped by bearings for suspending the concentrator frame 36 on the
horizontal axis 42. A large diameter elevation drive support arc 55
allows a gear motor with a sprocket and chain arrangement similar to the
azimuth drive with similar advantage. More than 180 degrees of motion
with the concentrator assembly 35 facing past straight up to directly
down is possible by simply extending the elevation support arc 55.
Setting the shafts/bearings on the horizontal axis 42 so that the
receiver 48 balances the concentrator assembly 35 minimizes loading and
elevation drive power required.

[0023]Most two axis trackers for photovoltaic panels, heliostats and point
focus solar collectors use a single pedestal. Although this lone
foundation and column are simple, interface modules that mount on the top
of the pedestal require dedicated castings or complex welded assemblies.
These assemblies have to transmit large dead and live (wind) loads from
the tracking structure to the pedestal and maintain tracking accuracy of
the drives and bearings for decades. Thousands of pounds of wind acting
on the wide sail area of the concentrator, say with a 36 foot diameter,
is typically counteracted by a gear with a small radius, typically less
than a foot, requiring precise (to minimize free motion) and very strong
gear teeth. To replace these primary drive components and associated
bearings typically requires removing the entire assembly from the
pedestal. These issues limit single pedestal designs to around 800 square
feet of active area.

[0024]To avoid concentrating forces through the small interface on top of
a single pedestal, a variety of related art solar collectors use
turntables that distribute support to multiple foundations. Turntables
which do not use spokes would be quite small (concentrators less than 200
square feet) because the rings required for transmitting the wind forces
involved in larger concentrators would be too heavy. Turntables which use
spokes (supporting concentrators up to 5,400 square feet) are limited by
the requirements to prevent uplift. If uplift (or overturning) forces are
transmitted through the hub, very large forces are involved unless the
length of the moment arm (the radius of the turntable ring) is also large
which adds considerable weight to these assemblies. To prevent uplift
through the connections between the turntable ring and multiple
foundations for the rollers that support the ring and allow for rotation
require accurately assembled mechanisms to capture the ring under all
conditions.

[0025]Heliostats, solar furnaces, and point-focus solar collector systems
utilize concentrators consisting of either a single monolithic reflector,
one made of a parabolic array of mirrors or a Fresnel arrangement of
mirrors. These systems follow the apparent daily and seasonal movement of
the sun by two separate motions. Reflectors of both heliostats and solar
furnaces direct sunlight to a stationary focal region. In a point focus
solar collector system, the receiver typically moves along with the
reflector. Point-focusing dish solar concentrators provide much higher
optical and operating performance than any other type and have high
temperature capability (3,000 degrees Fahrenheit and above), use minimal
land, and are highly modular (power plant sizes from single kilowatts to
many megawatts). Accordingly, such dish concentrator systems are very
versatile and are adaptable to many markets for solar applications,
particularly for generating electric power in both remote and
community-scale installations, as well as providing industrial process
heat, producing high value chemicals, making renewable fuels (hydrogen),
and destroying toxic wastes.

[0026]Foundations, mechanical, electric, instrumentation, and
communication interfaces and the tracking modules of point-focusing solar
collector systems with related installation and quality control labor
account for a large part of the construction effort. Because these
subassemblies are similar for both large and small units, one can install
a single large solar collector much more readily than many smaller ones.
Structural issues begin to dominate this design approach for
concentrators larger than 10,000 square feet, more than ten times the 800
square foot limit for single pedestals.

[0027]Accordingly, there remains a continuing need to improve solar
collector systems for a wide range of commercial applications. Such solar
radiation collector systems should: [0028]be straightforward to
manufacture, ship and install using common materials and indigenous
facilities and not require expensive machinery or heavy equipment;
[0029]employ structures which are simple, strong, lightweight, and
capable of supporting large concentrators and heavy receivers;
[0030]tolerate extreme weather conditions including severe winds, hail,
freezing rain, snow, and the like without reducing performance;
[0031]allow ordinary people working together with hand tools to both
manufacture and assemble models appropriate for harvesting and utilizing
energy in their region; and [0032]have axes of rotation pass through the
center of gravity so it takes very little power to follow the sun or stow
the equipment.

SUMMARY OF THE INVENTION

[0033]A polar support configured for solar radiation collector systems or
related systems having structural members connecting two or more columns
that both support and anchor a gimbal carrying a solar concentrator, with
or without a receiver. An equatorial support includes structural devices
that allow the gimbal to both rotate and adjust the attitude for ease of
assembly and establish the axis parallel to the earth's polar axis.

[0034]A drive device may be provided for imparting a desired rotational
movement to the main support structure through a gimbal to effect a
desired primary tracking motion to adjust for the apparent daily motion
of the sun. The system can further include a drive device for moving the
transducer elements to provide for a second adjustment for the apparent
seasonal motion of the sun. When the transducer elements are reflecting
or refracting elements, the system also may include a suitable receiver
disposed at the point of focus for receiving the radiation. Direct energy
conversion devices constitute their own receiver. For a solar collector
system the receiver would be connected with the main support structure
and would move with it on one or both axes, whereas for a solar furnace
or a heliostat the receiver would be fixed at a desired location
independent of the main support structure.

[0035]A solar radiation collector system can include a ground support, and
a gimbal rotatably anchored at a first part of the ground support device
to have a rotation orientation. The gimbal includes a gimbal rim mounted
on the gimbal, which supports at least one radiation transducer element
and a suspension member, connected to a second part of the ground support
device, suspending the gimbal rim. A capture device connects to a driver
and passes over the gimbal rim to rotate the gimbal rim and keep the
gimbal rim in contact with the suspension member. The rotation
orientation desired for tracking motion is adjusted for an apparent
motion of the sun.

[0036]A method for assembling a solar radiation collector can include
fixing a ground support on the ground, assembling a gimbal with a gimbal
rim at one end of the gimbal, lifting the gimbal onto a second part of
the ground support, redirecting the gimbal, so at least one part of the
gimbal rim is close to the ground, assembling a transducer element on the
gimbal rim, anchoring a bottom of the gimbal on a second part of the
ground support, and adjusting a face of the transducer element so the
transducer element can face the sun.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037]The foregoing and other objects, features, and many of the attendant
advantages of the present technology will become apparent and better
understood upon reading the following detailed description considered in
conjunction with the accompanying drawings wherein:

[0038]FIG. 1 is a perspective view of a related art two-axis tracking,
solar collector system which follows the daily apparent movement of the
sun by rotating the concentrator assembly in right ascension on an RA
axis parallel to the axis of the earth, adjusts the declination angle of
the concentrator elements to accommodate the other required motion and
supports a curved rim on two polar support rollers.

[0039]FIG. 2 is a perspective view of a related art two-axis tracking,
solar collector system similar to the type described in FIG. 1 which
supports the tracking structure between polar and equatorial columns and
is driven in right ascension by a drive and wheel arrangement at the
equatorial column, and rotates the 28 mirror assemblies to accommodate
the second tracking motion.

[0040]FIG. 3 is a perspective view of a related art two-axis tracking,
solar collector system mounted on a single pedestal which follows the
daily apparent movement of the sun by rotating the concentrator assembly
in azimuth on a vertical axis, and pivots the concentrator assembly in
elevation on a horizontal axis to accommodate the other required motion.

[0041]FIG. 4 is a perspective view of a related art two-axis tracking,
solar radiation collector system that follows the daily apparent movement
of the sun by rotating a turntable in azimuth around a central vertical
axis, and pivots the concentrator assembly on an elevated horizontal axis
between two structures to accommodate elevation motion.

[0042]FIG. 5 is a perspective view of an embodiment of the solar collector
system technology that includes a gimbal which rotates on an RA axis
parallel to the axis of the earth, with the gimbal rim on one end
suspended on a flexible member that ends in two collars attached to two
polar columns and with the gimbal end opposite said rim rotatably mounted
on an equatorial foundation.

[0043]FIG. 6A is an early step in assembling the collector of FIG. 5 with
the gimbal partially assembled and its polygonal rim close to the ground.

[0044]FIG. 6B is the next step in assembling the collector with the fully
assembled gimbal oriented with the RA axis of rotation parallel to the
axis of the earth.

[0045]FIG. 6C illustrates another step in assembling the collector with
the gimbal positioned for installing the main support structures and
connecting the concentrator truss devices that establish the shape of the
parabolic dish.

[0046]FIG. 6D is perspective View 6D shown in FIG. 6B that shows details
of a gimbal orienting fixture that enables the equatorial end of the
gimbal to be raised and lowered or fixed at an appropriate attitude in
between.

[0047]FIG. 6E is perspective View 6E shown in FIG. 6B that shows details
of gimbal lifting devices with redirection mechanisms inserted into the
tops of the polar columns and lifting members that raise and lower gimbal
rim suspension collars that support and capture the rim of the gimbal.

[0048]FIG. 6F is yet another step in assembling the collector installing
the reflector support membranes and mirrors, utilizing a temporary
platform that rides on the two main support structures.

[0049]FIG. 6G is the final step in assembling the collector of FIG. 5 with
the gimbal oriented so the concentrator structure faces the ground for
mounting the receiver.

[0050]FIG. 6H is a front view of the completed solar collector showing the
counterweight.

[0051]FIG. 7A is a section view 7A in FIG. 6B, that shows details of the
suspension, capture and drive components that interface the polygonal rim
of the gimbal, with only one quadrant of the polygonal gimbal rim
visible, for clarity.

[0052]FIG. 7B is perspective view 7B in FIG. 7A, that shows the details
shown in FIG. 7A from a different angle in a larger scale.

[0053]FIG. 8A is a view of an assembled gimbal oriented with the RA axis
of rotation parallel to the axis of the earth that uses an RA drive
integrated with the gimbal rim structure.

[0054]FIG. 8B shows, in a perspective view of the gimbal rim, routing of
the flexible device used to both move and capture the gimbal rim, an
associated right ascension drive mechanism, the two gimbal rim suspension
collars, and the flexible suspension device, with one quadrant of the
polygonal gimbal rim visible, for clarity.

[0055]FIG. 8C is perspective view 8C of FIG. 8B that shows, in a side
view, the items shown in FIG. 8B.

[0056]FIG. 8D is a close-up of the RA drive portion of FIG. 8C that shows
that the RA drive transfers the flexible capture device from one side of
a gimbal rim roller to the other.

[0057]FIG. 8E is a close-up from the same perspective as FIG. 8D of
another RA drive option that uses wire rope for the flexible capture
device for both the primary motion and preventing uplift, and uses
webbing for suspending the gimbal rim.

[0058]FIG. 9A is a side view of the collector shown in FIG. 5 showing one
suitable arrangement for providing the second tracking motion:
declination.

[0059]FIG. 9B is a close up view of the declination drive shown in FIG. 9A
that uses link chain.

[0060]FIG. 10A is a perspective view of a solar radiation collector system
arranged as a solar furnace wherein the receiver is fixed along the axis
of rotation of the main supporting structure near the equatorial end
thereof, and independent of the main support structure.

[0061]FIG. 10B is a perspective view of a solar radiation collector system
arranged as a solar furnace where the receiver is fixed along the axis of
rotation of the main support structure near the polar end thereof and
independent of the main support structure.

[0062]FIG. 10C is the solar radiation collector system shown in FIG. 10B
during construction. It shows a concentrator access platform above the
attached transducer support membrane and in position for mounting
transducer elements.

[0063]FIG. 10D and FIG. 10E are close-ups of the RA drive indicated as
View 10D of FIG. 10B and View 10E of FIG. 10D that show the drive using
roller chain as the flexible force transmitting device.

DETAILED DESCRIPTION

[0064]A support for tracking structures is simple, strong, lightweight,
and capable of rigidly holding both large concentrators with heavy
receivers and small solar collectors.

[0065]This technology may provide a simple, low power, rigid primary drive
for accurately following the sun or other target in strong buffeting
winds.

[0066]This technology may allow few widely spaced foundations with simple
interfaces to both rotatably support and anchor the structure.

[0067]This technology may provide a tracking support structure which may
be constructed from sets of readily fabricated pieces which are easily
put together into compact subassemblies for shipping and then rapidly
assembled at the site.

[0068]This technology may provide a way to elevate and lower tracking
structures with common portable equipment so that construction personnel
can assemble and repair components near ground level and elevate the
structure safely, by hand, for operation.

[0069]While this technology is applicable to a wide range of
electromagnetic radiation collector systems and to other systems which
require precise single or two-axis tracking for an assembly, it is
especially appropriate for solar radiation collector systems, solar
furnaces, and heliostats and will be described for these embodiments.

[0070]Also, the technology will be described in detail as being
equatorially oriented, with the right ascension, RA, axis parallel to the
axis of the earth, however, it is to be understood that this is merely
for convenience and that the technology is not limited to this particular
orientation since this construction can also function if the solar
collector primary axis of rotation is at another angle. Moreover at
equinox, the plane of the concentrator can be either generally
perpendicular to the plane of the gimbal rim or disposed at some other
angle. For example, at equinox, the concentrator frame and transducer
elements carried thereby may be disposed at an angle that averages
between 40 to 50 degrees with respect to the axis of rotation to permit
the "fixed focus" operation of a solar furnace through the seasons as
shown, for example, in FIGS. 10A and 10B. Latitude, season, time and its
location relative to the tower determine the relationship between a
heliostat concentrator, the central receiver and the sun.

[0071]Furthermore, the technology may employ gimbals to support tracking
structures. Gimbals typically would have members that form a rim at one
end in combination with a simple pivot at the other end. For some
applications, e.g., FIGS. 10A and 10B, suspending the rim without the
offset pivot may be appropriate. These rims, that may be polygonal or
arcuate, are supported and anchored so that the gimbals are stable at all
orientations and both the rim and pivot ends, when utilized, of the
gimbals can be raised and lowered. For example, in a preferred
embodiment, three foundations support the gimbal. The rim of the gimbal
may be both supported by at least one suitable structural device and be
anchored by a second similar structural device, and when using flexible
members, one of these can also provide the primary horizon to horizon
tracking motion. The main tracking support structure of this technology,
in addition to being very strong and lightweight is capable of supporting
large, heavy loads and distributing radial loads through the gimbal rim
interface members directly to the ground at all orientations of the main
support structure. This approach can be readily both manufactured and
installed with common hand tools.

[0072]Multiple transducer elements may be carried by the concentrator
frame passing through the gimbal rim and provide for a desired
utilization of solar radiation. The combination of the concentrator frame
and the transducer elements carried by such frame form a solar
concentrator assembly. The transducer elements may be, for example,
reflector or refractor type elements for directing the solar radiation to
a suitable receiver or multiple receivers.

[0073]Alternatively, the transducer elements may be direct energy
conversion devices, such as photovoltaic cells or the like. For use with
conventional photovoltaic concepts, arrays of cells which utilize either
natural sunlight or concentrating modules can be employed. The system may
further include suitable ground support and stabilization devices for
rotatably supporting the main gimbal from the ground with stabilization
in three dimensions and allowing at least ninety degrees of rotation of
the main support structure with respect to the ground. The support and
stabilization devices may rotatably support and capture the rim on
primarily one end of the gimbal and rotatably supports another point
outside the plane of the rim or at opposing positions on the rim
providing effective three-dimensional stability that distributes dead and
live loads to suitably spaced foundations.

[0074]In describing directions in this document, the term equatorial will
be used for "toward the equator" and polar will denote "toward a pole".
When describing the tilt of an axis or location of solar collector
foundations, these terms avoid having to reference whether a description
is for the northern or southern hemisphere. Otherwise, the terms "north"
and "south" when used in solar motion directions in the northern
hemisphere would have to be changed to "south" and "north" in the
southern hemisphere.

[0075]Although suspension, capture and drive techniques described in this
application can be implemented using accurately formed rigid arcuate
components such as rings, hoops and gears, the preferred embodiments use
very strong, flexible structural members such as link chain, cable, and
webbing. These members naturally take shapes required for performing
mechanical duties without machining or pre-forming. They are also
inexpensive and easy to transport. In properly designed systems, these
flexible structural members are extremely strong, do not fatigue, do not
require periodic lubrication, and evenly distribute loads among
interfaces. This technology extends their use beyond where they have been
proven in suspension bridges, cargo restraining systems, and in lifting
equipment including hoists, elevators and cranes.

[0076]FIG. 5 shows a solar collector system 30 that includes a gimbal 75
that rotates on an RA axis 49 parallel to the axis of the earth, with the
polygonal gimbal rim 77 on the gimbal upper end riding on suspension
member 99 of FIG. 6, see FIG. 7A, suspended between two suspension
collars 82 attached to two polar columns 59 and with the lower end of the
gimbal 75 rotatably mounted at the equatorial foundation 52 utilizing an
RA axis support 72. The RA drive 69 uses a flexible member to force the
rim toward the suspension member 99 to prevent polar winds from lifting
the assembly. The gimbal and foundation structures enable two workers
with common tools such as winches, chain hoists, come-alongs and jacks to
raise the solar collector system for operation and lower it for
maintenance or to minimize exposure for class 5 hurricanes.

[0077]As described in FIG. 7A and FIG. 7B, a loop of link chain or cable
provides capture device 95 by connecting the RA drive 69 on top of one
gimbal rim suspension collar 82 and passing over the top of the gimbal
rim 77 to the RA force transmitting redirection mechanism 74 on top of
the gimbal rim suspension collar 82 on the opposite side. This loop is
utilized by the RA drive to pull the gimbal 75, with the tracking solar
collector 30, in either direction. Tension in this loop forces the gimbal
rim 77 against suspension member 99 attached to the polar columns 59
through the gimbal rim suspension collars 82, see FIG. 9A, and insures
that wind from a polar direction does not lift the gimbal 75. Pretension
in the suspension/capture can most easily be introduced by incorporating
a tensioning device that lengthens the loop path in the RA drive device
redirection mechanism 74. The two gimbal rim suspension collars 82 also
prevent the solar collector system 30 moving in high winds from the east
or west.

[0078]The polygonal gimbal rim 77 in FIG. 5 and subsequent figures has
eight sides which allow four gimbal rim rollers 70 on the lower half
sharing support and those on the upper half capturing the gimbal rim 77,
respectively. Larger solar collector systems 30 may require more gimbal
rim rollers 70 resulting in the polygonal rim having 8, 12, 16, or more
sides and an equal number of gimbal rim rollers at the intersections of
these sides. Also, the upper portion of the concentrator 35 and the
concentrator truss devices 103 have been divided into three equal parts
by two main support structure devices 32. This allows the concentrator
truss devices 103 to be manufactured, packaged and shipped in equal
length bundles. Equally valid for larger structures would be an approach
that divides the upper portion of the concentrator 35 and the
concentrator truss devices 103 into four equal parts with two symmetrical
central portions between the two main support structure devices 32. This
would establish a different relationship between the relevant dimensions
of the gimbal 75 and the concentrator assembly 35 than illustrated in
these figures that would be work in a similar manner. Also, these figures
were created to clearly illustrate the construction details involved in
building the gimbal 75 with polygonal gimbal rims 77 and associated
concentrator assemblies. As shown, the portion of the gimbal rim 77
between the concentrator assembly 35 and receiver 48 would both shade
some transducer elements 37 and block redirected sunlight reflecting off
others from reaching the receiver 48. Techniques to minimize these
effects are not emphasized in this work.

[0079]Common hand tools allow the gimbal 75, the concentrator assembly 35,
receiver booms 40 and receiver assembly 48, illustrated and described
under FIG. 6A through FIG. 6H, to be assembled near the ground and raised
for operation or lowered either for maintenance or to minimize exposure
to a category 5 hurricane.

[0080]FIG. 6A shows the first step in erecting a solar collector. Lifting
redirection mechanisms 97 are inserted into the tops of two polar columns
59 mounted on the polar foundations 50. The gimbal polygonal rim 77 is
assembled near the ground and gimbal rim rollers 70 inserted at each
corner of the polygon, illustrated in FIG. 7A. Two gimbal rim suspension
collars 82 are mounted on opposite sides of the gimbal rim 77 and
suspension member 99 attached. The midsection of the gimbal 75 is erected
on top of the gimbal rim 77. Lifting devices 91 are then used to lift the
partially assembled gimbal high enough so that it can be turned toward
the equatorial foundation 52. This figure also shows one of two support
structure pivots 34 which engage corresponding components mounted on the
two main support structure devices 32.

[0081]FIG. 6B illustrates the fully assembled gimbal 75 mounted between
the two polar columns 59 and the equatorial foundation 52. In locations
where freezing precipitation occurs, a gimbal rim radial cover 80 that is
stationary and gimbal rim top face panels 81 that are attached and move
with the gimbal rim 77 would protect the RA drive 69 and suspension
member 99 shown in FIG. 7A from precipitation at all orientations. A
second set of gimbal rim top face panels 81 can be attached on the bottom
side of the gimbal rim 77 to prevent wasps and birds from entering this
portion of the structure. At this point the attitude of the gimbal 75 is
adjusted so that the axis of rotation is parallel to the axis of the
earth by verifying that the angle between the gimbal axis outer tube 78
and a horizontal level is equal to the site latitude and that it lies
over a line of longitude.

[0082]FIG. 6C has lifting devices 91 change the orientation of the gimbal
75 so that the two main support structures 32 that support the
concentrator truss devices 103 can be inserted inside the gimbal rim 77.
Main structure ground supports 109 may be placed to stabilize the two
main support structures 32 while mounting concentrator assembly 35 and
declination drive 67 components.

[0083]FIG. 6D is a close up view of the components associated with the RA
axis support 72 and those used to control the gimbal's 75 orientation.
The solar collector system 30 is designed to minimize the power required
for the drives by locating the center of gravity of the assembled
concentrator assembly 35 and receiver 48 on the centerline of the gimbal
rim 77 shown in FIG. 6A as the support structure pivot 34. As a result,
the gimbal rim 77 and polar columns 59 support the weight of the moving
structure and the RA axis support 72 is lightly loaded so that it takes
little effort to adjust the orientation of the assembly.

[0084]FIG. 6E is perspective View 6E shown in FIG. 6B that shows details
used during construction of a gimbal lifting device that utilizes a
flexible force transmitting device 46 with lifting redirection mechanisms
97 inserted into the tops of the polar columns 59. These are used in
conjunction with lifting device 91, see FIG. 6B, to raise and lower
gimbal rim suspension collars 82. Once a fastener through hole 92
connects a gimbal rim suspension collars 82 to the polar column 59, its
lifting device 91, flexible force transmitting device 46 and lifting
redirection mechanisms 97 can be removed and used for another
installation.

[0085]FIG. 6F has the transducer support membrane 107 in place and three
rows of transducer elements 37 mounted. A concentrator access platform
105 that rides on the top members of the two main support structures 32
during the construction phase can facilitate the assembly process. In
addition to supporting the transducer elements 37, the transducer support
membrane 107 provides diagonal bracing for the front face of the
structure. One effective material for this function is corrugated metal
or plastic because it is lightweight and the corrugations facilitate both
their attachment to the concentrator truss devices 103 and the transducer
elements 37 to the support membrane 107. Corrugations facilitate warping
the material in three dimensions so that it establishes the required
accurate paraboloidal surface for mounting reflective transducer elements
37. Straight plastic corrugated materials readily take the required
curvature on site. Heavier metal corrugated materials may be formed with
a radius of curvature that is the average radius of the concentrator
parabola and then deformed during assembly to match the very slight
difference required for the parabolic shape. PV panels can be fastened
directly to straight concentrator truss devices 103 without utilizing a
transducer support membrane 107.

[0086]FIG. 6G shows the collector system 30 reoriented so that it faces
the ground to facilitate mounting the receiver booms 40 and receiver
device 48. Also visible is the counterweight 121 added to balance the
receiver device 48 and the concentrator components above the gimbal rim
77 that don't have corresponding items below the rim. Structural bracing
devices 119 attached to the concentrator truss devices 103 on the side
opposite the transducer support membrane 107 creates stiffness that
effectively transmits torque from wind and gravity loads on the
concentrator assembly 35 to the gimbal rim 77 and prevent twisting that
would diminish the performances of the solar collector system 30.

[0087]FIG. 6H clearly shows the counterweight 121 in this view of the
solar collector system 30 at solar noon.

[0088]FIG. 7A, perspective View 7A in FIG. 6B, shows, in section, details
of the components that interface the polygonal rim 77 of the gimbal 75,
with only one quadrant of the polygonal gimbal rim 77 visible, for
clarity. This figure illustrates the arrangement of the components
associated with suspension, capture and the preferred method of driving
the polygonal gimbal rim 77. The weight of the tracking structure is
borne by gimbal rim rollers 70 mounted at each junction of the polygonal
rim 77 that ride on suspension member 99 shown as link chain. Each end of
this chain is anchored to opposing gimbal rim suspension collars 82.
During erection and maintenance these gimbal rim suspension collars 82
are suspended from the tops of the polar columns 59 as described under
FIG. 6E. When assembly has been completed, the collars 82 are fastened
directly to the polar columns 59. Since these collars engage the gimbal
rim rollers 70 and limit motion to the east and west they should be
longer than the distance between adjacent rollers so that they each
engage at least one RA roller 70 on each side at all times.

[0089]The following are reasons for the preferred approach for mounting
the RA drive 69 on the stationary gimbal rim suspension collars 82:
[0090]1. This system uses a shorter length of capture device 95 and its
installation is straightforward; [0091]2. The gear motor and associated
components are always located at the same place where they are readily
accessible and easily serviced; [0092]3. The gimbal rim rollers are
simple, each with a single interface that engages both the suspension
member 99 while in the lower region, and the capture device 95 while in
the upper region; and [0093]4. This approach allows continuous rotation
from east to west, without having to return in the opposite direction for
installations where circuits and fluid lines do not restrict this mode of
operation.

[0094]Reasons for incorporating the RA drive 69 with the gimbal rim 77 so
that it moves with the tracking structure will be covered later.

[0095]The RA drive 69 powered by a gear motor 57 is mounted on one gimbal
rim suspension collar 82 and a force transmitting member redirection
mechanism 74 mounted on the other gimbal rim suspension collar 82. A loop
of capture device 95, illustrated by link chain, passes over the top of
the gimbal rim 77. One half of the loop circuit follows the same path on
the gimbal rim rollers 70 as the suspension member 99. The other half of
the link chain loop fits into force transmitting device engagement
mechanisms 117 incorporated with each gimbal rim roller 70. This link
chain loop is utilized by the RA drive 69 to pull the gimbal 75, with the
tracking solar collector 30 attached, east or west. Tension in this chain
forces the gimbal rim 77 against suspension member assembly 82/99 and
insures that wind from a polar direction cannot lift the gimbal 75.
Because tension in each half of the chain loop is equal, this doubles the
preload force on the suspension member assembly 82/99.

[0096]FIG. 7B is perspective View 7B in FIG. 7A, that shows the details of
the RA drive devices 69 shown in FIG. 7A from a different angle and in a
larger scale. Both the force transmitting member redirection mechanism 74
and the RA drive 69 incorporate additional link chain rollers to insure
that the gimbal rim rollers 70 make a smooth transition between the chain
loop and the gimbal rim suspension collars 82, the profile of which
should match the shape of chain as it rides on the gimbal rim rollers 70.
The dotted arrows shown on FIG. 7B indicate that the force transmitting
member engagement mechanisms 117 capture the appropriate half loop of the
capture device 95 and the chain and the force transmitting member
engagement mechanisms 117 move together when pulled by the RA drive 69.
The other half of the loop travels in the opposite direction, shown by
solid arrows, and rides on the gimbal rim rollers 70.

[0097]FIG. 8A is a view of an assembled gimbal oriented with the RA axis
of rotation parallel to the axis of the earth that uses an RA drive 69
integrated with the polygonal gimbal rim 77 structure and also
illustrates strap ratchets, another type of lifting device 91, cargo
strapping, for raising and lowering the gimbal 75. Incorporating the RA
drive 69 into the gimbal rim enables power and control cables to be short
and within the "Faraday cage" of the moving structure.

[0098]In contrast to the RA drive 69 embodiment shown in FIGS. 7A and 7B
where the gear motor 57 is mounted on a gimbal rim suspension collar 82
and does not move with the gimbal 75, the two RA drives 69 illustrated in
FIG. 8A through FIG. 8F are mounted within the gimbal rim 77 and move
with the solar collector systems 30. Reasons for incorporating the RA
drive 69 on the tracking structure are: [0099]1. The simplest and most
reliable source of power for operating a point focus solar collector 30
is a dedicated deep cycle battery charged by a sunlight power module,
both located on the moving structure. Like power for starting vehicles,
autonomous power in a solar collector insures that there is power
available for stowing the system if communications fail, power required
by either drive exceeds a set limit, or weather becomes severe. It is the
most simple way and uses the least materials to collocate the battery
with one drive or with the on board controller and to have short cables
to the other drive and sensors. [0100]2. Point focus solar collectors 30
work best in open areas where they can intercept sunlight an entire day
without shading by trees or buildings. This also makes them susceptible
to lightning. The metal structures: gimbal 75, the concentrator assembly
35 and receiver 48 with booms 40 form a Faraday cage that keeps static
electricity on the outside. Substantial static charges do not build up
internally so that electronic assemblies are easier to protect inside
this cage than are wires coming from outside. [0101]3. For an autonomous
system, battery, PV charging panel, drive and sensor modules with short
wiring harnesses can be quality tested together and quickly installed.
Subsystems not located on the tracking structure typically require wiring
and quality testing be done during construction. [0102]4. Communications
and control technologies now include optical fiber and wireless
techniques that are very reliable in areas exposed to lightning. Solar
systems that generate the power they need onboard require only a
communication channel, ideally one that does not use copper conductors,
which can be very reliable.

[0103]The preferred version of this technology utilizes an RA drive 69
that is stationary, by attaching it to a gimbal rim suspension collar 82
fastened to one of the polar columns 59. Many turntable type solar
collectors, illustrated in FIG. 4, utilize a sprocket on the shaft of a
gear motor 57 to drive roller chain attached to a large diameter ring.
This technique can readily be used for driving the gimbal rim 77 but
roller chains require lubrication which can be problematic, especially in
desert regions with a lot of abrasive dust. FIGS. 8A and 8B show an
approach that uses a loop of link chain, that does not require
lubrication, to drive the gimbal rim 77 and provide the capture device 95
pretension load. The solar collector gravity load and said pretension
load is carried by the suspension member 99.

[0104]FIG. 8B shows, in a plan view of the polygonal gimbal rim device 77
of FIG. 8A, routing of the flexible capture device 95 used to both move
and capture the gimbal rim, an associated right ascension drive mechanism
69, the two gimbal rim suspension collars 82, and suspension member 99,
with one quadrant of the polygonal gimbal rim 77 visible. Because the
central region of the gimbal rim rollers 70 rides on the suspension
member 99, and therefore not available for another flexible member, the
gimbal rim rollers 70 must include two additional regions for interfacing
the capture device 95. The capture device 95 is first fastened to a
gimbal rim suspension collar 82 at A and wrapped around the inboard
grooves of the gimbal rim rollers 70 and to the RA drive 69 located in
one quadrant of the polygonal gimbal rim 77. The drive 69 transfers the
capture device 95 to the groove.

[0105]The flexible suspension device 99 starts at the bottom of the left
hand collar and extends to the bottom of the right hand collars. The
flexible capture device 95 starts at A and goes >500° to B.

[0106]FIG. 8D is a close-up of the RA drive portion outlined as View 8D of
FIG. 8C that shows that the RA drive 69 transfers the flexible capture
device 95 from one side of the gimbal rim roller 70 to the other and that
the rim rollers 70 ride on the central groove of the suspension member
99.

[0107]FIG. 8E is a close-up from similar perspective to FIG. 8D of another
RA drive 69 option that uses wire rope, also referred to as aircraft
cable, for the flexible capture device 95 for both the primary motion and
to prevent wind uplift, and uses webbing for suspension member 99 of the
polygonal gimbal rim 77. It illustrates the arrangement of the components
associated with suspension, capture and driving the polygonal gimbal rim
77 using this method. The weight of the tracking structure is distributed
through gimbal rim rollers 70 mounted at each junction of the polygonal
rim 77 that ride on suspension member 99 shown as webbing. Each end of
the webbing is anchored to opposing gimbal rim suspension collars 82.
During erection and maintenance these gimbal rim suspension collars 82
are suspended from the tops of the polar columns 59 as described under
FIG. 6E but in this application using webbing instead of link chain in
the lifting devices 91. In a manner similar to that described for link
chain under FIG. 7A, respective ends of two separate cables are fixed to
each of the two gimbal rim suspension collars 82 and pass over the top of
the gimbal rim 77 in opposite directions. They are utilized by the RA
drive 69 to pull the gimbal 75, with the tracking solar collector
attached 30, around the cable circuit. Tension in these cables insures
that wind from a polar direction forces the gimbal rim 77 against
suspension member 99 and does not lift the gimbal 75. Each cable is long
enough to make one and a half circuits around the rim and is tensioned to
the working limit of the cable. At solar noon when the concentrator
assembly 35 is facing the zenith and the RA drive 69 is near the ground,
an equal amount of cable is wrapped around the RA cable drum 115. The RA
cable drum 115 has spiral grooves to accommodate a single layer of cable.
The first cable is fixed to one end of the RA cable drum 115 and is
wrapped, following the spiral grooves to the middle of the cable drum.
The second cable is fixed to the other end of the RA cable drum 115 and
wrapped in the opposite direction until it meets the other cable at the
middle. As the RA cable drum 115 rotates counterclockwise, it pays out
the cable attached to the west gimbal rim suspension collar 82 and draws
in the other so that the cable junction interface proceeds from the cable
drum 115 center, at solar noon, to the upper end of the cable drum 115 at
the east limit and the concentrator is facing toward the ground, as in
FIG. 6F. Proceeding in the other direction from solar noon, the cable
interface junction proceeds from the cable drum 115 center to the lower
end of the cable drum 115 at the west limit and the concentrator again
faces the ground. To prevent fatigue of wires within the cable, the RA
cable drum 115 should be mounted so that the cables enter and leave on
the same side of the RA cable drum 115 as they engage the gimbal rim
rollers 70. When the gimbal rim rollers 70 are between points A and B in
FIG. 8C they must accommodate two capture device 95 (but in this case
cable) while in the balance of the circuit the rollers only engage a
single cable.

[0108]For the same reason RA drive 69 described under FIG. 8B routs the
link chain from one side of the gimbal rim roller 70 to the other, this
flexible cable drive routs the capture device 95 from one groove to the
one adjacent to it to prevent them from overlapping when the drive is
between the upper ends of the gimbal rim suspension collars 82.

[0109]An escapement device is required in this type of drive to keep the
cable interface location on the drum, where one cable winds off and the
other winds on, in line between the left cable groove of gimbal rim
roller 70 at CC and the right cable groove in corresponding roller at DD.
To keep this cable interface junction on the RA cable drum 115 in line
with the respective grooves in the adjacent gimbal rim roller 70, the RA
drive components can be mounted on linear support devices 113 and the
drive assembly moved left and right as one cable is wrapped on and the
other spooled out. One way to accomplish this is to utilize static
positioning devices 111 which has external threads with the same pitch as
the spiral grooves for cable in the RA cable drum 115 along with a region
with matching internal threads the drum axis. This static positioning
devices 111 is firmly attached to the linear support devices 113 by a
connector 116. As the RA cable drum 115 turns, it pulls itself to the
right as it pulls the polygonal gimbal rim 77 to the east keeping the
cable interface junction in line with the grooves in the two gimbal rim
rollers 70. For 0.125 inch OD cable (with a 1,600 pound working load)
with seven wraps per inch of drum, an Acme threaded rod with 7 threads
per inch and a matching nut mounted on the axis of the drum works well
for small systems. In a similar manner, when rotating in the other
direction, clockwise, turning the solar collector system 30 westerly, the
RA cable drum 115 counterclockwise (viewed from the right), it pushes
itself and the attached gear motor 57 along the linear support devices
113 to the left as it winds on the cable attached to the west gimbal rim
suspension collar 82.

[0110]FIG. 9A, a side view of the collector shown in FIG. 5, shows in
profile the preferred declination drive 67 that uses the same link chain
technology and many of the same parts as the preferred RA drive 69
described under FIG. 7A and FIG. 7B. The declination drive 67 also
utilizes link chain as a flexible force transmitting member 46, see FIG.
9B, to respective ends of a short length of drive support arc 55. An arc
length of 50° of declination motion 47 accommodates doubling the
tilt of the earth, 23.5° (from equinox to summer and winter
solstices) and an additional 3° for tracking off sun when there is
no call for power. This drive has to provide motion that accommodates the
23.5 degree tilt of the earth as it circles the sun. From equinox, the
sun travels this much above the ecliptic to the summer solstice and below
to the winter solstice. This motion also has to enable focused sunlight
to align just above the receiver when energy is not required and
therefore must cover a minimum of 50 degrees.

[0111]Any other suitable drive technology such as an electric linear
drive, hydraulic or pneumatic cylinder, and a roller chain sprocket
arrangement can also be utilized to accomplish this declination drive
task. Also visible in this view is the counterweight 121, which can form
a stiff integrating structural member between the two main support
structures 32 for the declination drive to act upon.

[0112]FIG. 9B shows a close up of View 9B in FIG. 9A of the declination
drive 67 that uses link chain for a flexible force transmitting member
46. This view also clearly shows the counterweight 121 that allows the
center of gravity of the moving system to coincide with the RA and
declination axes of rotation.

[0113]FIG. 10A is a perspective view of a solar radiation collector system
30 in accordance with this technology arranged as a solar furnace wherein
the receiver 48 is fixed along the RA axis of rotation 49 of the gimbal
75 in the equatorial direction and mounted on a separate foundation. This
embodiment, and those that follow, requires gimbal rim suspension collars
82, in this example four are connected together, fix the gimbal and
gimbal rim combination 75/77 so it is stable in wind from any direction
and can change orientation for construction and erection. Although the
suspension and capture devices in these embodiments are arcuate members,
they primarily utilize tensile strength (and therefore lightweight) with
the gimbal rim inside primarily working under compression. Incoming rays
of sunlight at equinox are parallel to the plane of the gimbal rim 77 and
are directed into the receiver 48 by the paraboloidal concentrator
assembly 35. A variety of techniques can be employed to raise, lower and
orient the gimbal rim 75/77 combination. Either the two polar column
devices 59 with foundations 50 and/or the equatorial column devices 84
with foundations 52 can be pivoted at each end and made of two sizes of
structural members where one fits snugly inside the other and telescopes.
In this illustration the polar column devices 59 are fixed and the
equatorial column devices 84 telescope and pivot at both ends. With the
two polar columns 59 fixed, and coaxial pin joints at the top,
lengthening and shortening the equatorial columns 84 controls the
orientation of the gimbal/gimbal rim 75/77 as illustrated in FIG. 10C.

[0114]The concentrator assemblies illustrated in both FIG. 10A and FIG.
10B simply pivot on an axis inside the gimbal rim 77, and direct
concentrated sunlight into the respective stationary receivers 48. The
relationship between the concentrator assembly 35, the sun and the
receiver changes through the seasons. For a fixed parabolic concentrator
assembly 35, this causes off-axis optical aberrations that would vary the
energy flux distribution available at the receiver 48 unless corrective
action, such as adding a device for warping the shape of the concentrator
assembly 35 as a function of declination angle. Another approach would
move the concentrator assembly 35 to maintain the
sun-concentrator-receiver relationship which would require moving the
entire concentrator in relation to the gimbals/rim devices 75/87 (along
with moving a counterweight in the opposite direction to keep the center
of gravity on the axis of rotation). Lower temperature applications, such
as cooking, and producing steam utilize an accommodating receiver opening
would not require this sophistication.

[0115]For solar furnaces and heliostats, as well as for solar collectors
where receivers move only in right ascension, the declination motion is
half the excursion of the sun from its position at equinox. For this
reason, the declination drive 67, in this case an electric motor powered
linear drive, not shown, need be only half as long as would be required
for a solar collector in which the receiver moves with the concentrator.
Details of the RA drive 69 are shown more clearly in FIG. 10D and FIG.
10E.

[0116]FIG. 10B is a perspective view of a solar radiation collector system
30 arranged as a solar furnace in accordance with another embodiment of
this technology wherein the receiver 48 is fixed along the RA axis of
rotation 49 of the gimbal/arcuate rim devices 75/87 in the polar
direction and mounted on a boom 40 with its own foundation.

[0117]This illustration is for a site at 34 degree latitude where the
plane of the gimbal/curved rim devices 75/87 is 56 degrees from
horizontal. Incoming rays of sunlight at equinox are parallel to the
plane of the gimbal/rim device 75/87 and are directed into the receiver
48 by the paraboloidal concentrator assembly 35.

[0118]FIG. 10C is the solar radiation collector system 30 shown in FIG.
10B during construction. It shows a concentrator access platform 105
above the attached transducer support membrane 107 and in position for
mounting transducer elements 37. An arrow next to the equatorial columns
84 indicates that as these telescoping tube sets are extended or
retracted, the orientation of the gimbal/arcuate rim 75/87 rotates around
the pivots on top of the polar columns 59. During construction the
equatorial columns 84 would be lengthened for easy access to the
concentrator access platform 105 from the ground and to give head
clearance for working inside the gimbal arcuate rim 75/87.

[0119]FIG. 10D and FIG. 10E are close-ups of the RA drive 69 indicated as
View 10D of FIG. 10B and View 10E of FIG. 10D that show the drive using
roller chain as the flexible force transmitting member 46. Also shown in
FIG. 10D is the cut for the section illustrating the engagement of a
gimbal rim roller 70 shown in FIG. 10E. A gear motor 57 with a drive
sprocket 89 on the output shaft engages the roller chain. A cutaway in
FIG. 10D shows gimbal rim rollers 70, in this example freely floating
crossed rollers with spacers in between adjacent rollers that support the
inner race, more clearly shown in FIG. 10E as the arcuate gimbal rim 87
inside the outer race, a continuous gimbal rim suspension collar 82. The
arcuate gimbal rim 87 has a drive member engagement mechanism 117 shown
as a groove to contain the flexible force transmitting member 46. The
ends of the member 46 could be fastened to the gimbal rim 87, or a loop
of the flexible member 46 could engage projections, not shown, that
prevent the member 46 from slipping along the drive member engagement
mechanism 117. RA drive member redirection mechanism 74 shown as idler
sprockets can be used to insure that the flexible force transmitting
member 46 fully engages RA drive sprocket 89. To prevent precipitation
from entering these components and freezing, two rain-shedding radial
gimbal rim covers should be attached to the stationery gimbal rim
suspension collar: one on the top half and another on the bottom half
with an angle (not shown) projecting inside the arcuate gimbal rim 87.

[0120]The foregoing examples utilize simple suspension members 99 attached
to the lower ends of gimbal rim suspension collars 82 and utilize capture
devices 95 to both insure that gimbal rim devices always engage the
suspension members 99 and as flexible members for the RA drive 69. This
arrangement simplifies construction and maintenance because the weight of
the solar collectors is carried by the suspension member 99 that should
not require attention. Except during high wind events, maintenance on the
RA drive 69 can be done at any orientation by simply relieving the
pretension of the flexible capture device 95. It may be appropriate in
some applications to add the RA drive function to the suspension 99 but
this may complicate construction and maintenance.

[0121]It is to be understood that the foregoing descriptions and specific
embodiments shown herein are merely illustrative of the best mode of the
invention and the principles thereof, and that modifications and
additions may be easily made by those skilled in the art without
departing for the spirit and scope of the invention, which is therefore
understood to be limited only by the scope of the appended claims.